Try a little Bar Keeper's Friend. It's a sink cleaner (scouring powder) with oxalic acid in it. Actually, I think that is FSR's active ingredient, too. Use just a little BKF on wet rag and rub only as much as you need to get the rust off. Yeah it's a little abrasive, but if nothing else works, it might. Follow up with the Starbrite Teflon polish.